Former U.S. Rep. Lou Frey Jr., a Winter Park Republican whose ambitions for state office led him twice to defeat, formally announced his candidacy for the GOP governor's nomination on Monday.

''I've got the experience, the integrity, the background and I've really got what this state needs as a governor,'' said Frey, a 51-year-old attorney who represented the 9th Congressional District from 1969 to 1979.

The Frey campaign made the announcement in Tallahassee, Tampa, Miami and Winter Park.

A New Jersey native, Frey left what was considered a highly promising congressional career in 1978 to run for governor. He lost the GOP primary to drugstore king Jack Eckerd and his running mate Paula Hawkins. Hawkins defeated Frey in the 1980 GOP primary for the U.S. Senate nomination.

Both of those campaigns taught Frey some hard lessons.

''I'm a realist. I've run over things and I've been run over,'' said the father of five who left politics after 20 years ''with nothing . . . no, less than nothing because I had a big campaign debt to pay.''

In this campaign Frey has two things that were missing in 1978 and 1980: money and the political expertise of Orlando GOP consultant Oscar Juarez.

Juarez served as Frey's chief aide during his 10 years in Congress but stayed out of the two losing campaigns. Juarez told Frey he couldn't win either of those, but convinced him this time would be different.

''Oscar has never been wrong,'' Frey said, adding that this campaign will be run by professionals with a healthy budget. Among his consultants is Richard Wirthlin, pollster to President Reagan.

One of the biggest disappointments of the 1978 race was $30,000 worth of television commercials that never aired because Frey's campaign ran out of money.

This time, he said, it will be different.

''I have ridden on a white horse into the sunset . . . I used to think that by energy, by my record and frankly by my intelligence, I could by force of will get there,'' he added.

However, he said to be a legitimate candidate ''you have to have money.''

He said he plans to raise $4 million and will report between $300,000 and $400,000 on his first campaign report due this week. His chief primary opponent, Tampa Mayor Bob Martinez, is expected to report about $900,000.

Though Frey left public life with more debts than assets, he quickly landed a job in one of the largest law firms in the county and proceeded to parley his legislative knowledge of communications law and regulations into ownership of five television stations, a number of radio stations and a license to operate the first transcontinental fiber optics cable between England and America.

The biggest issue in the race will be preserving the quality of life in Florida, Frey said. While he advocates no new taxes, he supports the concept of user fees to pay for government services.

Frey said he is confident a Republican can win in 1986, noting there have been gains in voter registration and that Republicans tend to turn out more voters than Democrats in non-presidential years.

Other Republicans in the race are Martinez, GOP state vice chairman Chester Clem, state Sen. William ''Doc'' Myers, R-Hobe Sound, and Rep. Tom Gallagher, R-Coconut Grove.